Ethylene-aromatic vinyl compound copolymer and method for its production

ABSTRACT

The present invention provides an ethylene-aromatic vinyl compound copolymer having an aromatic vinyl compound content of from 1 to less than 55% by molar fraction, and otherwise defined in the claims, and compositions and molded products containing same.

This application is a Division of application Ser. No. 09/203,488 Filedon Dec. 2, 1998, now U.S. Pat. No. 6,066,709, which is a continuation ofSer. No. 08/820,082, filed Mar. 19, 1997, now U.S. Pat. No. 5,883,213.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel ethylene-aromatic vinylcompound copolymer and a method for its production.

2. Discussion of Background

For the production of a copolymer of ethylene with an aromatic vinylcompound such as styrene, studies have been conducted primarily by usingso-called heterogeneous Ziegler-Natta catalysts (e.g. Polymer Bulletin20, 237-241 (1988)). However, conventional heterogeneous Ziegler-Nattacatalyst systems are not so practical, since the catalytic activitiesare low, the styrene content in the product is low, or the product doesnot have a uniform regular copolymer structure or contains a substantialamount of homopolymers.

Further, some ethylene-styrene copolymers obtainable by using so-calledhomogeneous Ziegler-Natta catalyst systems comprising a catalyst of atransition metal compound and an organoaluminum compound, and methodsfor their production have been known.

JP-A-3-163088 and JP-A-7-53618 disclose styrene-ethylene copolymerswherein no normal styrene chain is present i.e. so-called pseudo randomcopolymers, obtained by using a complex having a so-called constrainedgeometrical structure. Here, a normal styrene chain is meant for ahead-to-tail bond chain.

However, phenyl groups in the alternating structure of ethylene-styrenepresent in such pseudo random copolymers, have no stereoregularity.

Hereinafter, styrene and cyclopentadienyl may sometimes be representedby St and Cp, respectively.

JP-A-6-49132 and Polymer Preprints, Japan 42, 2292 (1993) disclosemethods for producing similar styrene-ethylene copolymers wherein nonormal St chain is present, i.e. so-called pseudo random copolymers, byusing a catalyst comprising a bridged Cp type Zr complex and acocatalyst.

However, according to Polymer Preprints, Japan 42, 2292 (1993), phenylgroups in the alternating structure of ethylene-styrene present in suchpseudo random copolymers, have no substantial stereoregularity.

On the other hand, a styrene-ethylene alternating copolymer obtainableby using a Ti complex having a substituted phenol type ligand, is known(JP-A-3-250007 and Stud. Surf. Sci. Catal. 517 (1990)). This copolymerhas a feature that it consists essentially of an alternating structureof ethylene-styrene and contains substantially no other structure suchas an ethylene chain, styrene chain, a structure comprising an ethylenechain and styrene, a structure of e.g. a head to head or tail to tailbond of styrene. The alternating degree (value λ in the presentspecification) of the copolymer is at least 70, substantially at least90.

Namely, the resulting copolymer is a copolymer having a very high degreeof alternation and consisting substantially solely of the alternatingstructure, whereby it is substantially difficult to change thecompositional ratio of the copolymer consisting of 50% of ethylene and50% of styrene by molar fraction.

Further, the stereoregularity of phenyl groups of which copolymer isisotactic, but the isotactic diad index m is about 0.92.

Further, the weight average molecular weight of this copolymer is low ata level of 20,000, which is inadequate to provide practically usefulphysical properties. It should also be added that the catalyticactivities are very low, and the copolymer can hardly be regarded aspractically useful, since it is obtained as a mixture with e.g.syndiotactic polystyrene.

Further, Macromol. Chem., 191, 2387 (1990) has reported astyrene-ethylene copolymer prepared by using CpTiCl₃ as a transitionmetal compound and methyl alumoxane as a cocatalyst. It is disclosedthat at a certain specific transition metal compound/cocatalyst ratio, apseudo random copolymer free from a styrene chain can be obtainedalthough the catalytic activities are very low, but no disclose is givenwith respect to the stereoregularity of the ethylene-styrene alternatingstructure of the resulting copolymer.

In Eur. Polym. J., 31, 79 (1995), copolymerization of ethylene andstyrene is carried out under various conditions using the same catalyst.However, it is disclosed that obtained are syndiotactic polystyrene andpolyethylene only, and no copolymer is obtainable.

Macromolecules, 29, 1158 (1996) discloses that copolymerization ofethylene and styrene is carried out by means of CpTiCl₃ and a boron typecocatalyst to obtain a copolymer having a high degree of alternationtogether with syndiotactic polystyrene and polyethylene. However, nostereoregularity is observed in the ethylene-styrene is alternatingstructure.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an ethylene-aromaticvinyl compound copolymer containing an aromatic vinyl compound in anamount of from 1 to less than 55% by molar fraction, wherein thestereoregularity of phenyl groups in the alternating structure ofethylene and an aromatic vinyl compound contained in a proportion nothigher than a certain level, is an isotactic structure, and a method forits production.

The present invention provides an ethylene-aromatic vinyl compoundcopolymer having an aromatic vinyl compound content of from 1 to lessthan 55% by molar fraction (“% by molar fraction” will hereinafter berepresented by “mol %”), wherein the stereoregularity of phenyl groupsin the alternating structure of ethylene and an aromatic vinyl compoundrepresented by the following formula (1) contained in its structure, isrepresented by an isotactic diad index m of more than 0.75, and thealternating structure index λ represented by the following formula (i)is smaller than 70 and larger than 1:

λ=A3/A2×100  (i)

where A3 is the sum of areas of three peaks a, b and c attributable toan ethylene-aromatic vinyl compound alternating structure represented bythe following formula (1′), obtained by 13C-NMR, and A2 is the sum ofareas of peaks attributable to the main chain methylene and methinecarbon, as observed within a range of from 0 to 50 ppm by 13C-NMR usingTMS as standard,

where Ph is an aromatic group such as a phenyl group, and xa is aninteger of at least 2 representing the number of repeating units,

wherein Ph is an aromatic group such as a phenyl group, and xa is aninteger of at least 2 representing the number of repeating units.

Further, the present invention provides a method for producing theethylene-aromatic vinyl compound copolymer as defined above, whereinpolymerization is carried out by means of a transition metal compoundcontaining two unsubstituted or substituted indenyl groups or atransition metal compound containing one unsubstituted or substitutedcyclopentadienyl group and one unsubstituted or substituted indenylgroup, and a cocatalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a 1H-NMR chart of the polymer obtained in Example 10.

FIG. 2 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using chloroform-d as a solvent. Entire spectrum.

FIG. 3 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using chloroform-d as a solvent. Methine-methylene region.

FIG. 4 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using chloroform-d as a solvent. In the vicinity of 25 ppm.

FIG. 5 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. Entirespectrum.

FIG. 6 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 7 is a 13C-NMR spectrum of the polymer obtained in Example 1,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. In thevicinity of 25 ppm.

FIG. 8 is a 13C-NMR spectrum of the polymer obtained in Example 2,measured by using chloroform-d as a solvent. Entire spectrum.

FIG. 9 is a 13C-NMR spectrum of the polymer obtained in Example 2,measured by using chloroform-d as a solvent. Methine-methylene region.

FIG. 10 is a 13C-NMR spectrum of the polymer obtained in Example 2,measured by using chloroform-d as a solvent. In the vicinity of 25 ppm.

FIG. 11 is a 13C-NMR spectrum of the polymer obtained in Example 3,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. Entirespectrum.

FIG. 12 is a 13C-NMR spectrum of the polymer obtained in Example 3,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 13 is a 13C-NMR spectrum of the polymer obtained in Example 3,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. In thevicinity of 25 ppm.

FIG. 14 is a 13C-NMR spectrum of the polymer obtained in Example 4,measured by using chloroform-d as a solvent. Entire spectrum.

FIG. 15 is a 13C-NMR spectrum of the polymer obtained in Example 4,measured by using chloroform-d as a solvent. Methine-methylene region.

FIG. 16 is a 13C-NMR spectrum of the polymer obtained in Example 4,measured by using chloroform-d as a solvent. In the vicinity of 25 ppm.

FIG. 17 is a 13C-NMR spectrum of the polymer obtained in Example 6,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. Entirespectrum.

FIG. 18 is a 13C-NMR spectrum of the polymer obtained in Example 6,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 19 is a 13C-NMR spectrum of the polymer obtained in Example 6,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. In thevicinity of 25 ppm.

FIG. 20 is a 13C-NMR spectrum of the polymer obtained in Example 11,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. Entirespectrum.

FIG. 21 is a 13C-NMR spectrum of the polymer obtained in Example 11,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 22 is a 13C-NMR spectrum of the polymer obtained in Example 11,measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent. In thevicinity of 25 ppm.

FIG. 23 is a 13C-NMR spectrum of the polymer obtained in Example 12,measured by using chloroform-d as a solvent. Entire spectrum.

FIG. 24 is a 13C-NMR spectrum of the polymer obtained in Example 12,measured by using chloroform-d as a solvent. Methine-methylene region.

FIG. 25 is a 13C-NMR spectrum of the polymer obtained in Example 12,measured by using chloroform-d as a solvent. In the vicinity of 25 ppm.

FIG. 26 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 1, measured by using chloroform-d as a solvent. Entire spectrum.

FIG. 27 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 1, measured by using chloroform-d as a solvent.Methine-methylene region.

FIG. 28 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 1, measured by using chloroform-d as a solvent. In the vicinityof 25 ppm.

FIG. 29 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 2, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Entire spectrum.

FIG. 30 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 2, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 31 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 2, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.In the vicinity of 25 ppm.

FIG. 32 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 3, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Entire spectrum.

FIG. 33 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 3, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 34 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 3, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.In the vicinity of 25 ppm.

FIG. 35 is a 13C-NMR spectrum of the polymer (boiling THF solublefraction) obtained in Comparative Example 4, measured by usingchloroform-d as a solvent. Entire spectrum.

FIG. 36 is a 13C-NMR spectrum of the polymer (boiling THF solublefraction) obtained in Comparative Example 4, measured by usingchloroform-d as a solvent. Methine-methylene region.

FIG. 37 is a 13C-NMR spectrum of the polymer (boiling THF solublefraction) obtained in Comparative Example 4, measured by usingchloroform-d as a solvent. In the vicinity of 25 ppm.

FIG. 38 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 5, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Entire spectrum.

FIG. 39 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 5, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.Methine-methylene region.

FIG. 40 is a 13C-NMR spectrum of the polymer obtained in ComparativeExample 5, measured by using 1,1,2,2-tetrachloroethane-d2 as a solvent.In the vicinity of 25 ppm.

FIG. 41 is model structures used for peak shift prediction by 13C-NMRdata base STN SPECINFO.

FIG. 42 shows the peak prediction results by 13C-NMR data base STNSPECINFO.

FIG. 43 is a spectrum of the copolymer obtained in Example 11, measuredby a 13C-NMR DEPT method.

FIG. 44 is a GPC chart of the copolymer obtained in Example 11.

FIG. 45 is a GPC chart of a cold MEK insoluble fraction of the copolymerobtained in Example 11.

FIG. 46 is a 13C-NMR spectrum of a cold MEK insoluble fraction of thecopolymer obtained in Example 11.

FIG. 47 is a DSC chart of the copolymer obtained in Example 10.

FIG. 48 is a graph showing the styrene contents and the melting pointsof the copolymers in Examples, Comparative Examples and in literatures.

FIG. 49 is X-ray diffraction peaks of the copolymers obtained Examplesand Comparative Examples.

FIG. 50 is a S-S curve of the copolymer in the vicinity of a styrenecontent of 40 mol %.

FIG. 51 is a S-S curve of the copolymer in the vicinity of a styrenecontent of 30 mol %.

FIG. 52 is a S-S curve of the copolymer in the vicinity of a styrenecontent of 20 mol %.

FIG. 53 is a S-S curve of the copolymer in the vicinity of a styrenecontent of 13 mol %.

FIG. 54 is a S-S curve of the copolymer in the vicinity of a styrenecontent of 7 mol %.

FIG. 55 is a Time Course of the Relaxation of a sample of the copolymerobtained in Example 6.

FIG. 56 is a S-S curve of a sample of the copolymer obtained in Example9 having its crystallinity changed.

FIG. 57 is a S-S curve of a sample of the copolymer obtained in Example10 having its crystallinity changed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described in detail. In the followingdescription, Ph in chemical formulas represents an aromatic group suchas a phenyl group.

The copolymer of the present invention is an ethylene-aromatic vinylcompound copolymer having an aromatic vinyl compound content of from 1to less than 55 mol %, whereby the stereoregularity of phenyl groups inthe alternating structure of ethylene and an aromatic vinyl compoundrepresented by the formula (1) contained in its structure, isrepresented by an isotactic diad index m of more than 0.75 and thealternating structure index λ represented by the formula (i) is smallerthan 70 and larger than 1.

Its structure can be determined by a nuclear magnetic resonance method(NMR).

Now, the present invention will be described with reference to anethylene-styrene copolymer as a typical example of the copolymer of thepresent invention.

The 13C-NMR spectrum of this copolymer wherein the styrene content isfrom 1 to less than 55 mol % (from 3 to less than 82 wt %), shows peaksmainly at the following positions.

Namely, it shows peaks attributable to the main chain methylene andmethine carbon in the vicinity of 25 ppm, 27 ppm, 30 ppm, 36 ppm and 45ppm, peaks attributable to five carbon atoms of a phenyl groups notbonded to the polymer main chain in the vicinity of 126 ppm and 128 ppm,and a peak attributable to one carbon atom of a phenyl group bonded tothe polymer main chain in the vicinity of 146 ppm.

The index λ showing the proportion of the ethylene-styrene alternatingstructure contained in the copolymer, is defined by the followingformula (i):

λ=A3/A2×100  (i)

where A3 is the sum of areas of three peaks a, b and c attributable toan ethylene-aromatic vinyl compound alternating structure represented bythe following formula (1′), obtained by 13C-NMR, and A2 is the sum ofareas of peaks attributable to the main chain methylene and methinecarbon, as observed within a range of from 0 to 50 ppm by 13C-NMR usingTMS as standard,

wherein Ph is an aromatic group such as a phenyl group, and xa is aninteger of at least 2 representing the number of repeating units.

The copolymer of the present invention is characterized in that thealternating structure index λ is smaller than 70 and larger than 1,preferably smaller than 70 and larger than 5.

In the copolymer of the present invention, the stereoregularity ofphenyl groups in the alternating copolymer structure of ethylene andstyrene being an isotactic structure is meant for a structure whereinthe isotactic diad index m (or a meso diad fraction) is more than 0.75,preferably more than 0.85, more preferably more than 0.95.

The isotactic diad index m can be obtained by the following formula(iii) from an area Ar of the peak attributable to the r structure of themethylene carbon peak and an area Am of the peak attributable to the mstructure appearing in the vicinity of 25 ppm.

m=Am/(Ar+Am)  (iii)

The positions of the peaks may sometimes shift more or less dependingupon the measuring conditions or the solvent used.

For example, when chloroform-d is used as a solvent, and TMS is used asstandard, the peak attributable to the r structure appears in thevicinity of from 25.4 to 25.5 ppm, and the peak attributable to the mstructure appears in the vicinity of from 25.2 to 25.3 ppm.

When 1,1,2,2-tetrachloroethane-d2 is used as a solvent, and the centerpeak (73.89 ppm) of the triplet of 1,1,2,2-tetrachloroethane-d2 is usedas standard, the peak attributable to the r structure appears in thevicinity of from 25.3 to 25.4 ppm, and the peak attributable to the mstructure appears in the vicinity of from 25.1 to 25.2 ppm.

Here, the m structure presents a meso diad structure, and the rstructure represents a racemic diad structure.

Further, the copolymer of the present invention includes a copolymerwherein an index θ represented by the following formula (ii) is largerthan 70 when the St content is less than 45 mol % and larger than 50when the St content is at least 45 mol %:

θ=A1/A2×100  (ii)

where A1 is the sum of areas of peaks attributable to methine andmethylene carbon α to ε in the following formula (2′), as observedwithin a range of from 0 to 50 ppm by 13C-NMR using TMS as standard, andA2 is the sum of areas of peaks attributable to the main chain methyleneand methine carbon, as observed within a range of from 0 to 50 ppm by13C-NMR using TMS as standard:

wherein Ph is an aromatic group such as a phenyl group, xb is an integerof at least 2 representing the number of repeating units, y is aninteger of at least 1, which may be the same or different in therespective units, and z is 0 or 1, which may the same or different inthe respective repeating units. When z is 0, the direction for insertionof styrene to the polymer chain is the same, whereas when z is 1, thedirection for insertion of styrene to the polymer chain is not the samedirection, thus indicating a case where a head to head or tail to tailbond is contained.

Further, the copolymer of the present invention may sometimes contain ahead to head or tail to tail bond structure derived from styrene, asshown by the following formula (7) depending upon the polymerizationconditions, etc.:

Peaks of methylene carbon of the structure derived from a head to heador tail to tail bond of styrene in a conventional pseudo randomcopolymer having no stereoregularity, are known to be observed withintwo regions of from 34.0 to 34.5 ppm and from 34.5 to 35.2 ppm (PolymerPreprints, Japan 42, 2292 (1993)). Whereas, with the ethylene-styrenecopolymer of the present invention, a peak attributable to methylenecarbon of a head to head or tail to tail bond structure derived fromstyrene, is observed in a region of from 34.5 to 35.2 ppm, but nosubstantial peak is observed within a region of from 34.0 to 34.5 ppm.

This is one of the characteristics of the copolymer of thepresent-invention and indicates that a high level of stereoregularity ofphenyl groups is maintained even in the head to head or tail to tailbond structure derived from styrene.

Further, when the St content is at least 20 mol %, the copolymer of thepresent invention may contain a head-to-tail bond structure comprisingtwo styrene units, represented by the following formula (8) (hereinaftersometimes referred to as a limited head to tail styrene structure).

In any case, the ethylene-styrene copolymer of the present inventionshows no distinct peak of syndiotactic polystyrene (40.8 to 41.0 ppm),atactic polystyrene (40.5 to 41.0 ppm) or isotactic polystyrene in thevicinity of from 40 to 41 ppm in the 13C-NMR spectrum using TMS asstandard at any styrene content. Namely, a chain of an atactic,syndiotactic or isotactic polystyrene having a head-to-tail structure ofthe following formula (9), characterized by such a peak, is notsubstantially present.

wherein q is an integer of at least 3.

The ethylene-styrene copolymer of the present invention is characterizedin that it has a highly stereoregular alternating structure of ethyleneand styrene in combination with various structures such as ethylenechains having various lengths, head to head or tail to tail bonds ofstyrene and limited head to tail styrenes.

Further, with the ethylene-styrene copolymer of the present invention,the proportion of the alternating structure can be changed dependingupon the styrene content in the copolymer. The changeable range issubstantially such that the value λ obtainable by the above formula (i)is within a range of from 1 to less than 70.

The stereoregular alternating structure is a crystallizable structure.Accordingly, the copolymer of the present invention can be made to havevarious properties in the form of a polymer having a crystalline,non-crystalline, partially or microcrystalline structure, by controllingthe St content or the crystallinity by a suitable method. The value λbeing less than 70 is important in order to impart significant toughnessand transparency to a crystalline polymer, or to obtain a partiallycrystalline polymer, or to obtain a non-crystalline polymer.

As compared with a conventional ethylene-styrene copolymer having nostereoregularity, the copolymer of the present invention is improved invarious properties such as the initial tensile modulus, hardness,breaking strength, elongation and solvent resistance in various Stcontent regions at various degrees of crystallinity and thus exhibitscharacteristic physical properties as a thermoplastic elastomer, a novelcrystalline resin or a transparent soft resin.

To improve the crystallinity of the copolymer of the present invention,a common method used for other crystalline polymers (addition of aplasticizer or a nucleating agent such as a filler) can be employed asit is. Further, immersion into a poor solvent such as hexane, althoughsuch a method may be less practical or annealing at a temperaturesufficiently higher than the glass transition temperature may, forexample, be mentioned as a simple method for improving thecrystallinity. Further, the presence of the head-to-tail bond comprisingtwo styrene units (the limited head to tail styrene structure)contributes to the improvement particularly in the initial tensilemodulus and breaking strength of the copolymer and to the control of theproportion of the alternating structure represented by the above value λto a level not higher than a certain limit in a region where the Stcontent is relatively high.

In the foregoing, the ethylene-aromatic vinyl compound copolymer of thepresent invention has been described with reference to styrene as atypical example of the aromatic vinyl compound. However, the aromaticvinyl compound to be used for the copolymer of the present invention maybe styrene or various substituted styrenes such as p-methylstyrene,m-methylstyrene, o-methylstyrene, o-t-butylstyrene, m-t-butylstyrene,p-t-butylstyrene, p-chlorostyrene, o-chlorostyrene, and α-methylstyrene.Further, a compound having a plurality of vinyl groups in one molecule,such as divinylbenzene, may also be mentioned.

Industrially preferably, styrene, p-methylstyrene or p-chlorostyrene isemployed, and particularly preferred is styrene.

In the case where the aromatic vinyl compound monomer isα-methylstyrene, the copolymer is represented by the formulae

where Ph is a phenyl group, and xa is an integer of at least 2representing the number of repeating units, and

where Ph is a phenyl group, xb is an integer of at least 2 representingthe number of repeating units, y is an integer of at least 1, which maybe the same or different in the respective units, and z is 0 or 1, whichmay be the same or different in the respective repeating units.

The copolymer of the present invention usually has a weight averagemolecular weight of at least 10,000, preferably at least 30,000, takingthe physical properties of the copolymer into consideration.

The copolymer of the present invention is not necessarily a twocomponent copolymer and may contain other structures or may have othermonomers copolymerized, so long as the structure and thestereoregularity are within the above specified ranges. Copolymerizableother monomers include, for example, C₃₋₂₀ α-olefins such as propylene,and conjugated diene compounds such as butadiene. Further, it ispossible to employ at least two components selected from theabove-mentioned aromatic compounds such as p-chlorostyrene,p-t-butystyrene, p-methylstyrene and divinyl benzene.

Depending upon e.g. the polymerization conditions, an atactichomopolymer formed by thermal polymerization, radical polymerization orcationic polymerization of the aromatic vinyl compound may sometimes becontained in a small amount, but such an amount is not more than 10 wt %of the total amount. Such a homopolymer can be removed by extractionwith a solvent, but may be left as included, so long as such aninclusion brings about no particular problems on the physicalproperties.

The copolymer of the present invention can be used as a thermoplasticelastomer, a crystalline resin or a transparent soft resin, dependingupon its properties. Further, for the purpose of improving the physicalproperties, various additives or other polymers may be blended thereto.Further, a plurality of copolymers of the present invention differing inthe styrene content may be blended.

Further, the copolymer of the present invention may be used also as acompatibilizing agent.

Now, a method for producing the ethylene-aromatic vinyl compoundcopolymer of the present invention will be described in detail.

A transition metal compound preferably used in the present invention isa transition metal compound of the following formula (3) or (4):

Here, each of Ind1 and Ind2 is an unsubstituted or substituted indenylgroup and does not include an unsubstituted or substituted fluorenylgroup, and Ind1 and Ind2 may be the same or different from each other,

Y is carbon, silicon, germanium or boron having bonds to Ind1 and Ind2,and having suitable other substituents, such as a substituted alkylenegroup, a substituted silylene group, a substituted germilene group or asubstituted boron, which is substituted by hydrogen, a halogen, a C₁₋₁₅alkyl group, a C₆₋₁₀ aryl group, a C₇₋₄₀ alkylaryl group or atrialkylsilyl group, in which the substituents may be the same ordifferent, or may have a cyclic structure such as a cyclohexylidenegroup.

Y is, for example, —CH₂—, —CMe₂—, —CPh₂—, —SiH₂—, —SiMe₂—, —SiPh₂—, acyclohexylidene group or a cyclopentylidene group.

X is hydrogen, a halogen such as chlorine or bromine, an alkyl groupsuch as a methyl group or an ethyl group, an aryl group such as a phenylgroup, a silyl group such as a trimethysilyl group, or an alkoxy groupsuch as a methoxy group, an ethoxy group or an isopropoxy group.

M is a Group IV metal such as Zr, Hf or Ti.

For each of Ind1and Ind2, the unsubstituted indenyl group may, forexample, be 1-indenyl, and the substituted indenyl group may, forexample, be 2-alkyl-1-indenyl, 2,4-dialkyl-1-indenyl,2,4,6-trialkyl-1-indenyl, 4,5-benzo-1-indenyl,1-alkyl-4,5-benzo-1-indenyl, 2,5-dialkyl-1-indenyl,2,5,6-trialkyl-1-indenyl, 2,4,5-trialkyl-1-indenyl,2-alkyl-4-aryl-1-indenyl, 2,4-diaryl-1-indenyl, 2-aryl-1-indenyl,2,6-dialkyl-4-aryl-1-indenyl, 2-alkyl-5-aryl-1-indenyl,2-alkyl-5,6-diaryl-1-indenyl, 2-alkyl-4,5-diaryl-1-indenyl, or2-alkyl-4,6-diaryl-1-indenyl.

Here, Ind is an unsubstituted or substituted indenyl group and does notinclude an unsubstituted or substituted fluorenyl group.

Cp is an unsubstituted or substituted cyclopentadienyl group and doesnot include an unsubstituted or substituted indenyl group or fluorenylgroup.

Y is carbon, silicon, germanium or boron having bonds to Ind and Cp, andhaving other suitable substituents, such as a substituted alkylenegroup, a substituted silylene group, a substituted germilene group or asubstituted boron which is substituted by hydrogen, a halogen, a C-₁₋₁₅alkyl group, a C₆₋₁₀ aryl group, a C₇₋₄₀ alkylaryl group or atrialklysilyl group, wherein the substituents may be the same ordifferent, or may have a cyclic structure such as a cyclohexylidenegroup.

Y is, for example, —CH₂—, —CMe₂—, —CPh₂—, —SiH₂—, —SiMe₂—, —SiPh₂—, acyclohexylidene group or a cyclopentylidene group.

X is hydrogen, a halogen such as chlorine or bromine, an alkyl groupsuch as a methyl group or an ethyl group, an aryl group such as a phenylgroup, a silyl group such as a trimethylsilyl group, or an alkoxy groupsuch as methoxy group, an ethoxy group or an isopropoxy group.

M is a Group IV metal, such as Zr, Hf or Ti.

For Ind, the above-mentioned specific examples useful for Ind1 or Ind2of the above formula (3), can be used.

For Cp, the unsubstituted cyclopentadienyl group may, for example, becyclopentadienyl, and the substituted cyclopentadienyl group may, forexample, be 2-alkyl-4-aryl-1-cyclopentadienyl,2-alkyl-4,5-diaryl-1-cyclopentadienyl,2,5-dialkyl-4-aryl-1-cyclopentadienyl,2,4-dialkyl-5-aryl-1-cyclopentadienyl, 2-aryl-1-cyclopentadienyl,2-aryl-4-alkyl-1-cyclopentadienyl,2-aryl-4,5-dialkyl-1-cyclopentadienyl,2,3,4,5-tetraalkylcyclopentadienyl, 2,3,4,5-tetraalkylcyclopentadienyl,2-alkyl-1-cyclopentadienyl, 2,4-dialkyl-1-cyclopentadienyl,2,4,5-trialkyl-1-cyclopentadienyl, 2-trialkylsilyl-1-cyclopentadienyl,2-trialkylsilyl-4-alkyl-1-cyclopentadineyl, or2-trialkylsilyl-4,5-dialkyl-1-cyclopentadienyl.

In the transition metal compounds of the above formulas (3) and (4), Yis a group having bonds to Ind1 and Ind2, or to Ind and Cp, i.e. a groupof bridging them, and it plays a role of fixing the ligand structure andmaking the angle between metal M and the centroid of thecyclopentadienyl ring of the ligand, i.e. the so-called bite angle, in acase where no bridge group is present, smaller than the non-bridgedstate.

The following compounds may be mentioned as specific examples of suchtransition metal compounds.

Dialkylmethylenebis(1-indenyl)zirconium dichlorides, such asdimethylmethylenebis(1-indenyl)zirconium dichloride,diethylmethylenebis(1-indenyl)zirconium dichloride,di-n-propylmethylenebis(1-indenyl)zirconium dichloride,di-i-propylmethylenebis(1-indenyl)zirconium dichloride,methylethylmethylenebis(1-indenyl)zirconium dichloride, methyln-propylmethylenebis(1-indenyl)zirconium dichloride, methyli-propylmethylenebis(1-indenyl)zirconium dichloride, ethyln-propylmethylenebis(1-indenyl)zirconium dichloride, and ethyli-propylmethylenebis(1-indenyl)zirconium dichloride.

Cyclic alkylidenebis(1-indenyl)zirconium dichlorides, such ascyclohexylidenebis(1-indenyl)zirconium dichloride, andcyclopentylidenebis(1-indenyl)zirconium dichloride.

Diarylmethylenebis(1-indenyl)zirconium dichlorides, such asdiphenylmethylenebis(1-indenyl)zirconium dichloride.

Dialkylmethylene (1-indenyl) (substituted-1-indenyl)zirconiumdichlorides, such as dimethylmethylene(1-indenyl){(2-methyl-1-indenyl)}zirconium dichloride, dimethylmethylene(1-indenyl){(2-ethyl-1-indenyl)}zirconium dichloride, dimethylmethylene(1-indenyl){(2-phenyl-1-indenyl)}zirconium dichloride, dimethylmethylene(1-indenyl){(2-methyl-4-phenyl-1-indenyl)}zirconium dichloride,dimethylmethylene (1-indenyl){(4-phenyl-1-indenyl)}zirconium dichloride,dimethylmethylene (1-indenyl){(4-(1-naphthyl)-1-indenyl)}zirconiumdichloride, dimethylmethylene(1-indenyl){(2,4-dimethyl-1-indenyl)}zirconium dichloride,dimethylmethylene(1-indenyl){(2-methyl-4-(1-naphthyl)-1-indenyl)}zirconium dichloride,and dimethylmethylene (1-indenyl){(2,4-diphenyl-1-indenyl)}zirconiumdichloride.

Dialkylmethylene (substituted-1-indenyl)(substituted-1-indenyl)zirconiumdichlorides, such as dimethylmethylenebis{(2-methyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(2-ethyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(2-phenyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(2-methyl-4-phenyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(2,4-dimethyl-1-indenyl)}zirconiumdichloride,dimethylmethylenebis{(2-methyl-4-(1-naphthyl)-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(2,4-diphenyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(4-diphenyl-1-indenyl)}zirconiumdichloride, dimethylmethylenebis{(4-(1-naphthyl)-1-indenyl)}zirconiumdichloride,dimethylmethylene{(2-methyl-1-indenyl)}{(2-ethyl-1-indenyl)}zirconiumdichloride,dimethylmethylene{(2-methyl-1-indenyl)}{(2-phenyl-1-indenyl)}zirconiumdichloride,dimethylmethylene{(2-methyl-1-indenyl)}{(4-phenyl-1-indenyl)}zirconiumdichloride,dimethylmethylene{(2-phenyl-1-indenyl)}{(4-phenyl1-indenyl)}zirconiumdichloride,dimethylmethylene{(4-methyl-1-indenyl)}{(4-phenyl-1-indenyl)}zirconiumdichloride, and dimethylmethylene{(4-phenyl-1-indenyl)}{(4-(1-naphthyl)-1-indenyl)}zirconium dichloride.

Dialkylsilylene bis(1-indenyl)zirconium dichlorides, such asdimethylsilylene bis(1-indenyl)zirconium dichloride, diethylsilylenebis(1-indenyl)zirconium dichloride, di-n-propylsilylenebis(1-indenyl)zirconium dichloride, di-i-propylsilylenebis(1-indenyl)zirconium dichloride, methylethylsilylenebis(1-indenyl)zirconium dichloride, methyl n-propylsilylenebis(1-indenyl)zirconium dichloride, methyl i-propylsilylenebis(1-indenyl)zirconium dichloride, ethyl n-propylsilylenebis(1-indenyl)zirconium chloride, and ethyl i-propylsilylenebis(1-indenyl)zirconium dichloride.

Diarylsilylene bis(1-indenyl)zirconium dichlorides, such asdiphenylsilylene bis(1-indenyl)zirconium dichloride.

Dialkylsilylene (1-indenyl)(substituted-1-indenyl)zirconium dichlorides,such as dimethylsilylene (1-indenyl){(2-methyl-1-indenyl)}zirconiumdichloride, dimethylsilylene(1-indenyl){(2-ethyl-1-indenyl)}zirconiumdichloride, dimethylsilylene(1-indenyl){(2-phenyl-1-indenyl)}zirconiumdichloride,dimethylsilylene(1-indenyl){(2-methyl-4-phenyl-1-indenyl)}zirconiumdichloride, dimethylsilylene(1-indenyl){(4-phenyl-1-indenyl)}zirconiumdichloride,dimethylsilylene(1-indenyl){(4-(1-naphthyl)-1-indenyl)}zirconiumdichloride,dimethylsilylene(1-indenyl){(2,4-dimethyl-1-indenyl)}zirconiumdichloride,dimethylsilylene(1-indenyl){(2-methyl-4-(1-naphthyl)-1-indenyl)}zirconiumdichloride, anddimethylsilylene(1-indenyl){(2,4-diphenyl-1-indenyl)}zirconiumdichloride.

Dialkylsilylene (substituted-1-indenyl)(substituted-1-indenyl)zirconiumdichlorides, such as dimethylsilylene bis{(2-methyl-1-indenyl)}zirconiumdichloride, dimethylsilylene bis{(2-ethyl-1-indenyl)}zirconiumdichloride, dimethylsilylene bis{(2-phenyl-1-indenyl)}zirconiumdichloride, dimethylsilylenebis({(2-methyl-4-phenyl-1-indenyl)}zirconium dichloride,dimethylsilylene bis{(2,4-dimethyl-1-indenyl)}zirconium dichloride,dimethylsilylene bis{(2-methyl-4-(1-naphthyl)-1-indenyl)}zirconiumdichloride, dimethylsilylene bis{(2,4-diphenyl-1-indenyl)}zirconiumdichloride, dimethylsilylene bis{(4-diphenyl-1-indenyl)}zirconiumdichloride, dimethylsilylene bis{(4-(1-naphthyl)-1-indenyl)}zirconiumdichloride,dimethylsilylene{(2-methyl-1-indenyl)}{(2-ethyl-1-indenyl)}zirconiumdichloride,dimethylsilylene{(2-methyl-1-indenyl)}{(2-phenyl-1-indenyl)}zirconiumdichloride,dimethylsilylene{(2-methyl-1-indenyl)}{(4-phenyl-1-indenyl)}zirconiumdichloride,dimethylsilylene{(2-phenyl-1-indenyl)}{(4-phenyl-1-indenyl)}zirconiumdichloride,dimethylsilylene{(4-methyl-1-indenyl)}{(4-phenyl-1-indenyl)}zirconiumdichloride, anddimethylsilylene{(4-phenyl-1-indenyl)}{(4-(1-naphtyl)-1-indenyl)}zirconiumdichloride.

Dialkylmethylene(1-indenyl)(cyclopentadienyl) zirconium dichlorides,such as dimethylmethylene(1-indenyl)(cyclopentadienyl)zirconiumdichloride.

Cyclic alkylidene(1-indenyl)(cyclopentadienyl) zirconium dichlorides,such as cyclohexylidene(1-indenyl)(cyclopentadienyl)zirconiumdichloride.

Diarylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichlorides, suchas diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride.

Dialkylmethylene (substituted-1-indenyl)(cyclopentadienyl)zirconiumdichlorides, such asdimethylmethylene{(2-methyl-1-indenyl)}(cyclopentadienyl)zirconiumdichloride, anddimethylmethylene{(4-methyl-1-indenyl)}(cyclopentadienyl)zirconiumdichloride.

Dialkylmethylene (1-indenyl)(substituted-cyclopentadienyl)zirconiumdichlorides, such asdimethylmethylene{(1-indenyl)}(2-methyl-1-cyclopentadienyl)zirconiumdichloride, anddimethylmethylene{(1-indenyl)}(2,4-dimethyl-1-cyclopentadienyl)zirconiumdichloride.

In the foregoing, Zr complexes were exemplified. However, with respectto Ti complexes and Hf complexes, compounds similar to the above arepreferably employed. The foregoing complexes are used as racemicmodifications. However, D-isomers or L-isomers may also be employed.

In the present invention, an organoaluminum compound and/or a boroncompound is used as a cocatalyst together with the above transitionmetal compound.

As the organoaluminum compound to be used as a cocatalyst, analuminoxane (or an alumoxane) is preferred. The aluminoxane is a cyclicor chain compound of the following formula (5) or (6):

In the above formula (5), R is a C₁₋₅ alkyl group, a C₆₋₁₀ aryl group orhydrogen, and m is an integer of from 2 to 100 wherein each R may be thesame of different from one another.

In the above formula (6), each R′ is a C₁₋₅ alkyl group, a C₆₋₁₀ arylgroup or hydrogen, and n is an integer of from 2 to 100, wherein each R′may be the same or different from one another.

As the aluminoxane, methylalumoxane, ethylalumoxane ortriisobutylalumoxane is preferably employed. Particularly preferred ismethylalumoxane. If necessary, a mixture of these different types ofalumoxanes may be employed. Further, such an alumoxane may be used incombination with an alkylaluminum such as trimethylaluminum,triethylaluminum, triisobutylaluminum or a halogen-containingalkylaluminun such as dimethylaluminum chloride.

The boron compound to be used as a cocatalyst may, for example, beN,N-dimethylanilinium tetra(pentafluorophenyl) borate,trityltetra(pentafluorophenyl) borate, lithium tetra(pentafluorophenyl)borate or tri(pentafluorophenyl) borane.

Such a boron compound may be used in combination with theabove-mentioned organoaluminum compound. Especially when a boroncompound is used as a cocatalyst, it is effective to add analkylaluminum compound such as triisobutylaluminum to remove impurities,such as water, contained in the polymerization system, which adverselyaffect the polymerization.

By the method of the present invention, the ethylene-styrene copolymercan be produced with high catalytic activities and high productivity perunit catalyst, which has not be attained heretofore.

For the production of the copolymer of the present invention, ethylene,the above-mentioned aromatic vinyl compound, the transition metalcompound as a metal complex and the cocatalyst, are contacted. It ispossible to employ a method for carrying out the polymerization in aliquid monomer without using any solvent, or a method of using a singlesolvent or a mixed solvent selected from saturated aliphatic or aromatichydrocarbons or halogenated hydrocarbons, such as pentane, hexane,heptane, cyclohexane, benzene, toluene, xylene, chlorobenzene,chlorotoluene, methylene chloride or chloroform. If necessary, batchpolymerization, continuous polymerization, stepwise polymerization orpreliminary polymerization may be employed.

The polymerization temperature is usually from −78° C. to 200° C.,preferably from 0° C. to 160° C.

A polymerization temperature of −78° C. or lower is industriallydisadvantageous, and a temperature higher than 200° C. is not suitable,since decomposition of the metal complex will take place.

When an organoaluminum compound is used as a cocatalyst, it is usedrelative to the metal of the complex in an atomic ratio ofaluminum/complex metal of from 0.1 to 100,000, preferably from 10 to10,000. If this atomic ratio is smaller than 0.1, it tends to bedifficult to effectively activate the metal complex, and if it exceeds100,000, such is economically disadvantageous.

When a boron compound is used as a cocatalyst, it is employed in anatomic ratio of boron/complex metal of from 0.01 to 100, preferably from0.1 to 10, particularly preferably 1. If this atomic ratio is less than0.01, it tends to be difficult to effectively activate the metalcomplex, and if it exceeds 100, such is economically disadvantageous.

The metal complex and the cocatalyst may be mixed or formulated outsidethe polymerization tank or may be mixed in the tank during thepolymerization.

To the copolymer of the present invention, additives or adjuvants whichare commonly used for polymers, may be incorporated within a range notto adversely affect the effects of the present invention. Preferredadditives or adjuvants include, for example, an antioxidant, alubricant, a plasticizer, an ultraviolet ray absorber, a stabilizer, apigment, a colorant, a filler and a blowing agent.

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted to such specific Examples.

In the following description, Me represents a methyl group, Ind a1-indenyl group, Cp a cyclopentadienyl group, Flu a 9-fluorenyl group,Ph a phenyl group, and tBu a tertiary butyl group.

The analyses of copolymers obtained in Examples and Comparative Exampleswere carried out as follows.

The 13C-NMR spectrum was measured using TMS as standard, by using achloroform-d solvent or a 1,1,2,2-tetrachloroethane-d2 solvent, by JNMGX-270 or α-500, manufactured by Nippon Denshi Kabushiki Kaisha.

The 13C-NMR spectrum measurement for quantitative analysis of peakareas, was carried out by a proton gate decoupling method having-NOEerased, by using pulses with a pulse width of 45° and a repeating timeof 5 seconds as standard.

When the measurement was carried out under the same conditions exceptthat the repeating time was changed to 1.5 seconds, the measured valuesof peak areas of the copolymer agreed to the values obtained in the casewhere the repeating time was 5 seconds, within measurement error.

The styrene content in the copolymer was determined by 1H-NMR. JNMGX-270 or α-500, manufactured by Nippon Denshi Kabushiki Kaisha was usedas the apparatus. The determination was carried out by comparing theintensity of the proton peak attributable to a phenyl group (6.5 to 7.5ppm) and the proton peak attributable to an alkyl group (0.8 to 3 ppm),measured by using TMS as standard and chloroform-d or heavy1,1,2,2-tetrachloroethane-d2 as a solvent.

The molecular weights in Examples are obtained by GPC (gel permeationchromatography) as calculated as standard polystyrene.

A copolymer soluble in THF at room temperature, was measured by means ofHLC-8020, manufactured by Tosoh Corporation using THF as a solvent. Acopolymer insoluble in THF at room temperature, was measured by means ofGPC-7100, manufactured by Senshu Kagaku K. K. using1,2,4-trichlorobenzene as a solvent.

The DSC measurement was carried out by using DSC 200, manufactured bySeiko Denshi K. K. in a nitrogen stream at a temperature raising rate of10° C./min.

The X-ray diffraction was measured by means of MXP-18 model high powerX-ray diffraction apparatus, source Cu rotating anode (wavelength:1.5405 Å), manufactured by Mac Sience Company.

Test Examples

Preparation of Transition Metal Compounds

Rac-dimethylmethylenebis(1-indenyl)zirconium dichloride of the followingformula (another name: rac-isopropylidenebis(1-indenyl)zirconiumdichloride, hereinafter referred to as rac{Ind—C(Me)₂—Ind}ZrCl₂) wasprepared by the following two methods.

The first method is a synthesis as disclosed in New J. Chem., 14, 499(1990) or JP-A-3-100004. The second method is the following method.

Ligand 2,2-isopropylidene bis(1-indene) was prepared by the firstmethod.

In an argon atmosphere, 5 mmol of the ligand and 5 mmol of Zr(NMe₂)₄were dissolved in 30 ml of toluene, and the solution was heated andstirred at 140° C. for 15 hours under reflux. The solvent was distilledoff under reduced pressure, and 80 ml of dichloromethane was added.Then, 9 mmol of Me₂NH.HCl was added at −78° C., and the mixture wasstirred for one hour. The solvent was distilled off under reducedpressure, and then the residue was washed with pentane. The residualsolid was extracted with 200 ml of dichloromethane. After filtration,the liquid was concentrated under reduced pressure to obtain reddishorange crystals. The yield was 20%.

In the 1H-NMR spectrum measurement, the same complex obtained by eithermethod shows peaks at 6.92 to 7.80 ppm (m, 8H), 6.70 ppm (dd, 2H), 6.15ppm (d, 2H) and 2.37 ppm (s, 6H). In the following Examples, the complexobtained by the first method was used in Examples 1 to 7, and thecomplex obtained in the second method was used in Examples 8 to 11.Further, styrene and toluene used, were dehydrated ones.

Preparation of Copolymers

EXAMPLE 1

Into an autoclave having a capacity of 120 ml and equipped with astirrer, which was substituted by nitrogen and then by ethylene, 10 mlof styrene and 8.4 mmol, based on A1 atom, of methylalumoxane (MMAO-3A,manufactured by Tosoh-Akuzo K. K.) were charged. While supplyingethylene under an atmospheric pressure, 26 ml of a toluene solutioncontaining 8.4 μmol of the above-mentioned rac{Ind—C(Me)₂—Ind}ZrCl₂, wasadded by a syringe. Then, the pressure was immediately raised to 5kg/cm²G by ethylene, and the temperature was raised to 50° C. in aboutone minute. Thereafter, polymerization was carried out at 50° C. for onehour while maintaining the ethylene pressure at 5 kg/cm²G. Aftercompletion of the polymerization, ethylene was slowly released, and theliquid was put into a large excess amount of a mixed solution of dilutehydrochloric acid/methanol, whereupon a polymer was recovered. Therecovered product was dried at 60° C. for 10 hours under reducedpressure to obtain 7.5 g of the polymer.

EXAMPLE 2

Into an autoclave having a capacity of 300 ml and equipped with astirrer, which was substituted by nitrogen and then by ethylene, 20 mlof styrene, 60 ml of toluene and 8.4 mmol, based on A1 atom, ofmethylalumoxane (MMOA-3A, manufactured by Tosoh Akzo K. K.) werecharged. Ethylene was introduced at about 10° C. to raise the pressureto 9 kg/cm²G, whereupon a catalyst solution having 8.4 μmol of theabove-mentioned rac{Ind—C(Me)₂—Ind)ZrCl₂ dissolved in 40 ml of toluene,was introduced into the autoclave from a pressure resistant tankprovided on an upper portion of the polymerization reactor. Thereafter,polymerization was carried out for one hour while maintaining theethylene pressure at 10 kg/cm²G. During the polymerization, thetemperature of the reaction solution increased to the maximum of 52° C.due to heat generation. After completion of the polymerization, ethylenewas slowly released, and post treatment was carried out in the samemanner as in Example 1 to obtain 18.2 g of a polymer.

EXAMPLE 3

Polymerization and post treatment were carried out in the same manner asin Example 2 except that styrene was changed to 2 ml, and toluene waschanged to 78 ml. The liquid temperature increased to the maximum of 26°C. due to the polymerization heat. As a result, 3.1 g of a polymer wasobtained.

EXAMPLE 4

Polymerization and post treatment were carried out in the same manner asin Example 2 except that styrene was changed to 60 ml, toluene waschanged to 20 ml, the ethylene pressure was changed to 1 kg/cm²G, andthe autoclave was heated to maintain the reaction solution at 50° C.during the polymerization, whereby 3.4 g of a polymer was obtained.

EXAMPLE 5

Polymerization and post treatment were carried out in the same manner asin Example 4 except that the polymerization temperature was changed to12° C., and the ethylene pressure during the polymerization was changedto 0.5 kg/cm²G, whereby 3.0 g of a polymer was obtained.

EXAMPLE 6

Into an autoclave having a capacity of 1 l and equipped with a stirrer,which was substituted by nitrogen and then by ethylene, 80 ml ofstyrene, 360 ml of toluene and 8.4 mmol, based on A1 atom, ofmethylalumoxane (MMAO-3A, manufactured by Tosoh-Akuzo K. K.) werecharged. Ethylene was introduced at about 10° C. to raise the pressureto 9 kg/cm²G, whereupon a catalyst solution having 8.4 μmol of theabove-mentioned rac{Ind—C(Me)₂—Ind}ZrCl₂ dissolved in 40 ml of toluene,was introduced into the autoclave from a pressure resistant tankprovided at an upper portion of the polymerization reactor. Thereafter,polymerization was carried out for one hour while maintaining theethylene pressure at 10 kg/cm²G. During the polymerization, thetemperature of the reaction solution increased to the maximum of 70° C.due to heat generation. After completion of the polymerization, ethylenewas slowly released, and post treatment was carried out in the samemanner as in Example 1 to recover 97 g of a polymer.

EXAMPLE 7

Polymerization and post treatment were carried out in the same manner asin Example 6 except that the amount of the complex used, was changed to2.1 μmol, and the temperature at the time of introducing ethylene waschanged to 17° C. During the polymerization, the temperature of thereaction solution increased to the maximum of 93° C. due to heatgeneration. 58 g of a polymer was obtained.

EXAMPLE 8

Polymerization was carried out by using an autoclave having a capacityof 10 l and equipped with a stirrer and a jacket for heating andcooling.

4,000 ml of toluene and 800 ml of styrene were charged, and the internaltemperature was raised to 50° C. and stirring was initiated. Theinterior of the system was purged by bubbling about 100 l of drynitrogen, and 8.4 mmol of triisobutylaluminum and 84 mmol, based on A1atom, of methylalumoxane (MMAO3A, manufactured by Tosoh-Akuzo K. K.)were added thereto. Immediately, ethylene was introduced, and thepressure was stabilized at 10 kg/cm²G, whereupon about 50 ml of atoluene solution containing 8.4 μmol of catalystrac{Ind—C(Me)₂—Ind}ZrCl₂ and 0.84 mmol of triisobutylaluminum, was addedto the autoclave from a catalyst tank provided on the autoclave.Polymerization was carried out for 3 hours while maintaining theinternal temperature at 50° C. and the ethylene pressure at 10 kg/cm²G.After completion of the polymerization, the obtained polymerizationsolution was gradually put into vigorously stirred excess methanol tolet the formed polymer precipitate. The product was dried under reducedpressure at 60° C. until a weight change was no longer observed, whereby816 g of a polymer was obtained.

EXAMPLE 9

Polymerization and post treatment were carried out in the same manner asin Example 8 except that the charged amounts into the autoclave werechanged to 1,800 ml of styrene and 3,000 ml of toluene, the ethylenepressure was changed to 5 Kg/cm²G, the amount of the catalyst used, waschanged to 21 μmol, and the polymerization time was changed to 4.25hours. As a result, 800 g of a polymer was obtained.

EXAMPLE 10

Polymerization and post treatment were carried out in the same manner asin Example 8 except that the charged amounts into the autoclave werechanged to 4,000 ml of styrene and 800 ml of toluene, the ethylenepressure was changed to 5 Kg/cm²G, the amount of the catalyst used, waschanged to 84 μmol, and the polymerization time was changed to 4 hours.As a result, 1,660 g of a polymer was obtained.

EXAMPLE 11

Polymerization and post treatment were carried out in the same manner asin Example 8 except that the charged amounts into the autoclave werechanged to 4,000 ml of styrene and 800 ml of toluene, the ethylenepressure was changed to 1 Kg/cm²G, the amount of the catalyst used, waschanged to 84 μmol, and the polymerization time was changed to 7 hours.As a result, 1,220 g of a polymer was obtained.

Preparation of Transition Metal Compounds and Copolymers

EXAMPLE 12

Rac-isopropylidene (1-indenyl)(cyclopentadienyl)zirconium dichloride ofthe following formula (hereinafter referred to asrac-(Ind—C(Me)₂—Cp}ZrCl₂) was prepared with reference to New J. Chem.,14, 499 (1990).

Polymerization and post treatment were carried out in the same manner asin Example 1 except that 16 ml of a toluene solution containing 8.4 μmolof the above-mentioned rac-{Ind—C(Me)₂—Cp}ZrCl₂ as a transition metalcompound, was used. As a result, 8.2 g of a polymer was obtained.

Comparative Example 1

Diphenylmethylene (fluorenyl)(cyclopentadienyl) zirconium dichloride ofthe following formula (hereinafter referred to as {Flu—CPh₂—Cp}ZrCl₂),as an EWEN type Zr complex, was prepared with reference to J. Am. Chem.Soc., 110, 6255 (1988).

Into an autoclave having an capacity of 120 ml and equipped with astirrer, which was substituted by nitrogen and then by ethylene, 20 mlof styrene and 4.6 mmol of MAO were charged and heated to 40° C. Whilemaintaining the ethylene pressure at an atmospheric pressure, 46 μmol ofthe above-mentioned {Flu—CPh₂—Cp)ZrCl₂ dissolved in 20 ml of toluene,was added, and polymerization was carried out for one hour. During thepolymerization, the temperature was maintained at 40° C., and thepressure was maintained at atmospheric pressure (0 Kg/cm²G). After thepolymerization, post treatment was carried out in the same manner as inExample 1 to obtain 2.2 g of a polymer.

Comparative Example 2

Polymerization and post treatment were carried out in the same manner asin Example 8 except that the charged amounts into the autoclave werechanged to 4,000 ml of styrene and 800 ml of toluene, the ethylenepressure was changed to 3 Kg/cm²G, 168 μmol of {Flu—CPh₂—Cp}ZrCl₂ wasused as the catalyst, the amount of MAO was changed to 168 mmol based onA1, and the polymerization time was changed to 4 hours. As a result, 286g of a polymer was obtained.

Comparative Example 3

A CGCT (constrained geometrical structure) type Ti complex (tertiarybutylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silane titaniumdichloride of the following formula (hereinafter referred to as{CpMe₄—SiMe₂—NtBu}TiCl₂) was prepared with reference to JP-A-7-053618.

Polymerization was carried out in the same manner as in Example 2 exceptthat the above-mentioned {CpMe₄—SiMe₂—NtBu}TiCl₂ was used as atransition metal compound, whereby 11.5 g of a white polymer wasobtained.

Comparative Example 4

Polymerization and post treatment were carried out in the same manner asin Example 1 except that 16 ml of a toluene solution containing 23 μmolof the above-mentioned (CpMe₄—SiMe₂—NtBu}TiCl₂ , was used, and 23 mmolof MAO was used. As a result, 1.6 g of a polymer was obtained. As aresult of the analysis, the obtained polymer was found to be a mixtureof polyethylene, syndiotactic polystyrene and a copolymer. Therefore, itwas fractionated into a boiling THF soluble fraction and insolublefraction by means of a Soxhlet extractor.

Comparative Example 5

Polymerization and post treatment were carried out in the same manner asin Example 8 except that the charged amounts into the autoclave werechanged to 800 ml of styrene and 4,000 ml of toluene, the polymerizationtemperature was changed to 90° C., 84 μmol of {CpMe₄—SiMe₂—NtBu}TiCl₂was used as the catalyst, and the polymerization time was changed to onehour.

Consumption of ethylene was monitored, whereby it was found thatpolymerization substantially completed in one hour. As a result, 350 gof a polymer was obtained.

Comparative Example 6

Polymerization and post treatment were carried out in the same manner asin Example 8 except that 21 μmol of {CpMe₄—SiMe₂—NtBu}TiCl₂ was used asthe catalyst, the charged amounts into the autoclave were changed to1,500 ml of styrene and 3,300 ml of toluene, the polymerizationtemperature was changed to 50° C., and the polymerization time waschanged to 2.5 hours.

Consumption of ethylene was monitored, whereby it was found thatpolymerization substantially completed in 2.5 hours. As a result, 550 gof a polymer was obtained.

Comparative Example 7

Polymerization and post treatment were carried out in the same manner asin Example 1 except that 50 μmol of CpTiCl₃ was used as the catalyst,MMAO was changed to 5 mmol, the charged amounts into the autoclave werechanged to 20 ml of styrene and 20 ml of toluene, the polymerizationtemperature was changed to 40° C., and the ethylene pressure was changedto 1 Kg/cm²G. As a result, 0.5 g of a polymer was obtained. As a resultof the 13C-NMR and DSC analyses, the product was a mixture of mainlysyndiotactic polystyrene and polyethylene. By 13C-NMR, no peak wasobserved at 25.1 to 25.5 ppm.

The polymerization conditions and the polymerization results in therespective Examples and Comparative Examples are shown in Table 1.

TABLE 1 Amount Amount Amount Polymeri- Producti- of of of Ethylenezation Polymeri- Amount vity St catalyst toluene styrene pressure temp.zation obtained (g/mol · content (μmol) (ml) (ml) (kg/cm²G) (° C.) time(hr) (g) catalyst)/10⁶ (mol %) Example 1 8.4 26 10 5 50 1 7.5 0.89 39.1Example 2 8.4 60 20 10 10-52 1 18.2 2.2 31.7 Example 3 8.4 78 2 10 10-261 3.1 0.37 7.2 Example 4 8.4 20 60 1 50 1 3.4 0.40 49.4 Example 5 8.4 2060 0.5 12 1 3.0 0.36 52.0 Example 6 8.4 360 80 10 10-70 1 97 12 17.7Example 7 2.1 360 80 10 16-93 1 58 28 7.3 Example 8 8.4 4000 800 10 50 3816 97 12.8 Example 9 21 3000 1800 5 50 4.25 800 38 28.0 Example 10 84800 4000 5 50 4 1660 20 43.5 Example 11 84 800 4000 1 50 7 1220 15 49.3Example 12 8.4 16 10 5 50 1 8.2 1.0 37.9 Comparative Example 1 46 20 200 40 1 2.2 0.05 43.0 (atmospheric pressure) Comparative Example 2 1644000 800 3 50 4 286 1.7 21.1 Comparative Example 3 8.4 60 20 10 18-57 111.5 1.4 19.6 Comparative Example 4 23 16 10 5 50 1 1.6 0.07 — (THFinsoluble fraction) about 0.3 — — (THF soluble fraction) about 1.3 —45.0 Comparative Example 5 84 4000 800 10 90 1 350 4.2 7.8 ComparativeExample 6 21 3300 1500 10 50 1 550 26.2 13.0

1H-NMR spectrum of the polymer obtained in Example 10 was shown in FIG.1.

The 13C-NMR measurement was carried out by using TMS (tetramethylsilane)as standard and chloroform-d as a solvent. These polymers aresubstantially soluble in chloroform-d at room temperature. The copolymerof the present invention is substantially soluble in chloroform at roomtemperature when the styrene content is substantially at least 20 mol %.

Further, using 1,1,2,2-tetrachloroethane-d2 as a solvent, the 13C-NMRwas measured under heating to about 100° C. In this case, the centerpeak of the triplet of 1,1,2,2-tetrachloroethane-d2 was used asstandard, and on the basis that the shift value of this peak was 73.89ppm, shift values of peaks of the copolymer were determined.

In the methine and methylene carbon regions, peaks attributable to thefollowing, are shown. Symbols a to m are symbols representing carbonatoms shown in the chemical structures of the formulas (10) to (14).

Attribution of peaks was made by a literature (Macromolecules 13, 849,(1980)) and by 13C-NMR (two dimensional Inadequate method, DEPT method).

In a case where chloroform-d was used as a solvent, and TMS was used asstandard:

25.2 to 25.3 ppm (c)

36.6 to 36.7 ppm (b)

45.4 to 45.5 ppm (a)

27.5 to 27.7 ppm (f)

29.6 to 29.8 ppm (g)

36.7 to 37.0 ppm (e)

45.7 to 46.6 ppm (d, h)

34.8 to 35.0 ppm (i)

43.0 ppm (j)

44.0 to 46.0 ppm (k)

36.0 ppm (l)

25.0 ppm (m)

In a case where the center peak (73.89 ppm) of the triplet of1,1,2,2-tetrachloroethane-d2 was used as standard:

25.1 to 25.2 ppm (c)

36.4 to 36.5 ppm (b)

45.0 to 45.3 ppm (a)

27.2 to 27.6 ppm (f)

29.4 to 29.9 ppm (g)

36.5 to 36.8 ppm (e)

45.4 to 46.1 ppm (d, h)

34.5 to 34.9 ppm (i)

42.5 to 43.0 ppm (j)

44.0 to 46.0 ppm (k)

35.6 to 36.1 ppm (l)

24.8 to 24.9 ppm (m)

The above positions of peaks may shift more or less depending upon themeasuring conditions, the solvent used, etc.

wherein xa is an integer of at least 2 representing the number ofrepeating units.

Namely,

wherein y is an integer of at least 2 representing the number ofrepeating units.

wherein y is an integer of at least 1.

Attribution of peaks j to m was made by literatures such as Stud. Surf.Sci. Catal., 517, 1990, J. Appl. Polymer Sci., 53, 1453 (1994), J. C.Randall, J. Polymer Phys. Ed., 13, 901 (1975), G. J. Ray et al.,Macromolecules, 10, 773 (1977), EP-416815, JP-A-4-130114, and by thepeak shift prediction (FIGS. 41 and 42) by the 13C-NMR data base STN(Specinfo).

As a result, the peak in the vicinity of 43.0 ppm observed with thecopolymer of the present invention wherein the St content issubstantially at least 20 mol % when measured by using a chloroform-dsolvent, is attributable to methine carbon j of a structure in which twostyrene units are chained, and the peak in the vicinity of 36.0 ppm isattributable to methylene carbon 1 and the peak in the vicinity of 25.0ppm is attributable to methylene carbon m. Likewise, k is attributableto any one of peaks within a range of from 44 to 46 ppm.

The results (FIG. 43) of measurement of the copolymer of the presentinvention by a 13C-NMR DEPT method show that the peak in the vicinity of43.0 ppm is attributable to methine carbon, and the peaks in thevicinity of 36.0 and 25.0 ppm, are attributable to methylene carbon.This supports the above-mentioned results.

The shift values of Examples and Comparative Examples measured by13C-NMR using chloroform-d as a solvent and TMS as standard, are shownin Table 2. The literature values in Table 2 were taken fromMacromolecules, 13, 849 (1980).

The shift values of Examples and Comparative Examples measured by13C-NMR using 1,1,2,2-tetrachloroethane-d2 as a solvent, are shown inTables 3 and 4. The peak of the isotactic diad structure (m structure)observed at 25.26 to 25.30 ppm when chloroform-d was used as a solvent,is observed at 25.11 to 25.22 ppm when 1,1,2,2-tetrachloroethane-d2 isused as a solvent.

Except for Example 12, with copolymers obtained in Examples of thepresent invention, a peak attributable to the syndiotactic diadstructure (r structure) was not substantially observed.

Typical 13C-NMR charts are shown in FIGS. 2 to 40.

The positions of peaks by the 13C-NMR measurement may shift more or lessdepending upon the measuring conditions, the solvent used, the standardpeaks, etc.

Further, the positions of peaks are influenced more or less by theadjacent structures on both sides of the structure shown in the formulas(10) to (14). For example, in the case of a styrene-ethylene alternatingstructure, a certain peak shift, or a microstructure or shoulder of thepeak, will form by a long distance effect, depending upon whether or notthe adjacent structures are also similar alternating structures, styrenechain structures, ethylene chain structures, or head to head or tail totail bonds.

TABLE 2 Peak shift values (ppm) measured by 13C-NMR using TMS asstandard by using chloroform-d as a solvent Comparative LiteratureExample 4 values Comparative THF soluble Attribution *1 Example 1Example 2 Example 4 Example 5 Example 12 Example 1 fraction c m 25.225.26 25.26 25.26 25.26 25.30 25.30 25.25 r 25.4 — —  (25.47)*2 — 25.4725.47 25.46 a mm 45.4 45.44 45.44 45.44 45.45 45.45 45.45 45.43 mr 45.5— — — — 45.55 45.56 45.55 rr 45.6 — — — — — 45.78 45.68 b m (m) 36.636.62 36.62 36.62 36.61 36.64 36.63 36.64 m (r) 36.7 — Not analyzable as— — 36.70 36.74 36.73 r (m) 36.9 — peaks overlapped — — — 36.95 36.94 r(r) 37.0 — with Et block peaks. — — — 37.02 37.04 *1 Macromolecules, 13,849-852 (1980) *2 A very small peak was observed.

TABLE 3 Peak shift values (ppm) measured by 13C-NMR using1,1,2,2-tetrachloroethane-d2 as a solvent Example Example AttributionExample 1 Example 2 Example 3 Example 6 Example 7 Example 8 Example 9 1011 c m 25.12 25.12 25.18 25.12-25.17 25.17-25.22 25.12-25.21 25.11-25.1625.12 25.12 r — — — — — — — — — a mm 45.36 45.33 45.39 45.34 45.36 45.2545.17 45.09 45.09 mr — — — — — — — — — rr — — — — — — — — — b m (m)36.46 36.46 36.48 36.46 36.48 36.46 36.43 36.41 36.41 m (r) — — Notanalyzable Not analyzable Not analyzable Not analyzable Not analyzable —— r (m) — — as peaks over- as peaks over- as peaks over- as peaks over-as peaks over- — — r (r) — — lapped with Et lapped with Et lapped withEt lapped with Et lapped with Et — — block peaks. block peaks. blockpeaks. block peaks. block peaks. Note: Using1,1,2,2-tetrachloroethane-d2 as a solvent, the sample was heated anddissolved at 100° C. and then subjected to the measurement. The centerpeak of the triplet of tetrachloroethane by 13C-NMR had a shift value of73.89 ppm relative to TMS. Each peak shift value of a copolymer wascalculated relative to the center peak value of the triplet oftetrachloroethane being 73.89 ppm.

TABLE 4 Peak shift values (ppm) measured by 13C-NMR using1,1,2,2-tetrachloroethane-d2 as a solvent Comparative Example 4Comparative Comparative Comparative THF soluble Comparative ComparativeAttribution Example 1 Example 2 Example 3 fraction Example 5 Example 625.1-25.4 25.1-25.4 25.1-25.4 25.1-25.4 c m 25.16 Broad or Broad or25.11 Broad or Broad or r 25.30 multiplet multiplet 25.29 multipletmultiplet peaks peaks peaks peaks 45.2-45.9 45.2-45.9 45.2-45.945.2-45.9 a mm 45.25 Broad or Broad or 45.15 Broad or Broad or mr 45.32multiplet multiplet 45.25 multiplet multiplet rr 45.41 peaks peaks 45.37peaks peaks b m (m) 36.4-36.8 36.4-36.8 36.4-36.8 36.44 36.5-36.936.5-36.9 m (r) Broad or Broad or Broad or 36.54 Broad or Broad or r (m)multiplet multiplet multiplet 36.70 multiplet multiplet r (r) peakspeaks peaks 36.83 peaks peaks Note: Using 1,1,2,2-tetrachlorethane-d2 asa solvent, the sample was heated and dissolved at 100° C., and thensubjected to the measurement. The center peak of the triplet oftetrachlorethane by 13C-NMR had a shift value of 73.89 ppm relative toTMS. Each peak shift value of a copolymer was calculated relative to thecenter peak value of the triplet of tetrachloroethane being 73.89 ppm.

The index λ representing the proportion of the ethylene-styrenealternating structure contained in the copolymer obtained in eachExample, was obtained by the following formula (i):

λ=A3/A2×100  (i)

Here, A3 is the sum of areas of three peaks a, b and c attributable toan ethylene-aromatic vinyl compound alternating structure represented bythe following formula (1′) obtained by 13C-NMR.

wherein Ph is an aromatic group such as a phenyl group, and xa is aninteger of at least 2 representing the number of repeating units.

Further, A2 in the formula (i), is the sum of areas of peaksattributable to the main chain methylene and methine carbon, as observedwithin a range of from 0 to 50 ppm by 13C-NMR using TMS as standard.

It is also-the sum of all peaks a to m in the formulas (10) to (14) andother peaks attributable to the main chain structure.

The copolymer of the present invention will have a value λ of at most60, since an ethylene chain structure, a styrene head to head or tail totail bond and a limited styrene head to tail chain structure arecontained in a substantial amount, even when the styrene content issubstantially 50 mol %.

The value θ of the copolymer obtained in each Example was determined bythe following formula (ii):

θ=A1/A2×100  (ii)

Here, A1 is the sum of areas of peaks attributable to methine andmethylene carbon a to e in the following formula (2′), as observedwithin a range of from 0 to 50 ppm by 13C-NMR using TMS as standard.Further, A2 is the sum of areas of peaks attributable to the main chainmethylene and methine carbon, as observed within a range of from 0 to 50ppm by 13C-NMR using TMS as standard.

wherein Ph is an aromatic group such as a phenyl group, xb is an integerof at least 2 representing the number of repeating units, y is aninteger of at least 1, which may be the same or different in therespective repeating units, and z is 0 or 1, which may be the same ordifferent in the respective repeating units.

The carbon atoms α to ε in the structure of the above formula (2′)corresponds to carbon atoms a to g in the structures of the aboveformula (10), (11) and (12).

Values λ and θ obtained in the respective Examples are shown in Table 5.

The isotactic diad index m of the copolymer obtained in each Example wasdetermined by the above formula (iii). Values m obtained in therespective Examples and Comparative Examples are shown in Table 6.

TABLE 5 St content (mol %) Value λ Value θ Example 1 39.1 43 91 Example2 31.7 37 96 Example 3 7.2 4.4 100 Example 4 49.4 58 78 Example 5 52.055 77 Example 6 17.7 10 98 Example 7 7.3 3.2 100 Example 8 12.8 6.1 99Example 9 28.0 22 96  Example 10 43.5 51 91  Example 11 49.3 59 83 Example 12 37.9 21 89

TABLE 6 Isotactic diad Melting Mw Mn fraction point (/10⁴) (/10⁴) Mw/Mn(m) (° C.) Example 1 14.0 6.3 2.2 >0.95 82, 98 Example 2 21.7 11.41.9 >0.95 98 Example 3 12.3 7.3 1.7 >0.95 96 Example 4 8.1 4.3 1.9 >0.9593 Example 5 16.6 7.8 2.1 >0.95 90 Example 6 14.8 5.2 2.8 >0.95 79Example 7 — — — >0.95 88 Example 8 17.2 8.4 2.0 >0.95 82 Example 9 16.09.0 1.8 >0.95 98 Example 10 14.8 7.5 2.0 >0.95  94, 107 Example 11 15.58.8 1.$ >0.95 91 Example 12 1.1 0.5 2.2 0.85 Not observed Comparative14.6 8.4 1.7 0.65 Not observed Example 1 Comparative 50.2 18.6 2.7 0.725 Example 2 Comparative 26.0 16.0 1.6 0.5 41 Example 3 Comparative — —— — 127, 274 Example 4 Polyethylene THF insoluble and S- fractionpolystyrene Comparative 16.6 5.5 3.0 0.5 (127) Example 4 PolyethyleneTHF soluble fraction Comparative 5.9 1.9 3.1 0.5 86 Example 5Comparative 19.0 12.0 1.6 0.5 63 Example 6

A GPC chart of the copolymer obtained in Example 11 is shown in FIG. 44.The copolymer completely dissolved in THF as a solvent.

Further, the obtained copolymer was dissolved in a small amount oftoluene and then put into methylethylketone (MEK) in an amount of about1,000 times by volume of the toluene and further cooled to −60° C. tofractionate into a cold MEK insoluble fraction (at least about 95 wt %of the entire polymer) and a cold MEK soluble fraction.

A GPC chart of the cold MEK insoluble fraction is shown in FIG. 45. Eachof the GPC curves showed a monodispersed single peak. The weight averagemolecular weights Mw, the number average molecular weights Mn and themolecular weight distribution Mw/Mn, obtained from a IR detector and anUV detector are as shown in Tables 7 and 8.

TABLE 7 Results of Example 11 (dissolved in THF) Average molecularweight Molecular GPC Weight Number weight detector average averagedistribution RI 155000 88000 1.76 UV 139000 55000 2.52

TABLE 8 Results of Example 11 (cold MEK insoluble fraction) Averagemolecular weight Molecular GPC Weight Number weight detector averageaverage distribution RI 139000 85000 1.63 UV 132000 78000 1.70

Although there may be measurement errors, the molecular weights and themolecular weight distributions obtained from the IR detector and the UVdetector show good agreement especially with the cold MEK insolublefraction (at least 95% of the entirety), because atactic polystyrene orthe like derived from radical polymerization or cationic polymerization,which was contained in a small amount, was removed. Further, themolecular weight distribution is not higher than 1.7, thus indicatingthat the copolymer of the present invention is a polymer having a highlevel of uniformity in both the molecular weight and the composition.

A 13C-NMR chart of the cold MEK insoluble fraction is shown in FIG. 46.The peak attributable to the atactic polystyrene slightly observed inthe vicinity of 41 ppm before the fractionation, has completelydisappeared with the cold MEK insoluble fraction. However, the peakattributable to the chain of two styrene units observed in the vicinityof 43 ppm, is still present, and its intensity is not substantiallychanged from prior to the fractionation. Further, even with the MEKinsoluble fractions obtained by changing the temperature of MEK at thetime of the fractionation (about 30% and 50% of the entirety), the peakat 43 ppm is present with substantially the same intensity. That is, thelimited head to tail styrene is uniformly present in the copolymer.

The DSC measurement of the polymer obtained in each example was carriedout, whereby the melting point was observed. The measurement wasconducted under such a condition that the temperature raising rate was10° C. per minute from −100° C.

As an example of the results of the DSC measurement, a chart of Example10 is shown in FIG. 47. The melting points of the respective Examplesare shown in Table 6.

Further, the relation between the styrene content and the melting pointis shown in FIG. 48.

The styrene-ethylene copolymers obtained in Comparative Examples 1 and 4(THF soluble) did not show a melting point.

The melting points of polymers obtained in Comparative Examples 2, 3 and5 are shown in Table 6 and also in FIG. 48.

ANTEC, 1634 (1996), discloses a relation between the styrene content andthe melting point of an ethylene-styrene copolymer obtained by using aso-called CGCT complex. This relation is shown in the same Figure forcomparison with the copolymer of the present invention. The styrenecontent was indicated as calculated as a molar fraction.

The copolymer of the present invention has a characteristics such thatit shows a melting point of from about 55 to 130° C. at a styrenecontent of from 1 to 55 mol %, particularly from 70° C. to 120° C. at astyrene content of from 10 to 55 mol %. This indicates that thecopolymer of the present invention is a crystallizable polymer withinthe entire range of this styrene content.

Whereas, copolymers obtained by using a CGCT complex or an EWEN typecomplex, exhibit melting points only within a range where the styrenecontent is not higher than 20 mol %. Besides, such melting pointsrapidly decrease as the styrene content increases, and it will be 70° C.or lower at a styrene content of at least 10 mol % and will be a levelof room temperature at a styrene content of 20 mol %. As disclosed inANTEC, 1634 (1996), the melting point of the copolymer derives from thepolyethylene crystalline structure, and it is a non-crystalline polymerat a styrene content of 20 mol % or higher.

To more clearly show that the copolymer of the present invention is acrystalline polymer, the results of the X-ray diffraction of thecopolymer are shown. FIG. 49 shows the results of the X-ray diffractionof copolymers obtained in Examples. Hollow peaks are omitted. With eachpolymer, the diffraction peaks specific to the copolymer of the presentinvention were observed, and the diffraction peak intensity increases asthe styrene content increases. The positions of diffraction peaks of thecopolymer of the present invention are different from the positions ofdiffraction peaks of polyethylene, syndiotactic polystyrene andisotactic polystyrene. When the styrene content is lower than about 15mol %, a diffraction peak of polyethylene is additionally observed.

The copolymer obtained in Comparative Example 2 was subjected to theX-ray diffraction measurement, whereby no diffraction peak was observed.

With the copolymer obtained in Comparative Example 5, only thediffraction peak attributable to polyethylene was observed.

The copolymer of the present invention has a crystalline structurederived from the stereoregularity of the styrene-ethylene alternatingregion, in a case where the styrene content is at least 10 mol %.

At a styrene content of from 10 to 55 mol %, the copolymer of thepresent invention exhibits excellent physical properties as athermoplastic elastomer i.e. high strength, low permanent elongation,solvent resistance and transparency. At a styrene content of from 1 toless than 10 mol %, it shows excellent properties as a transparent softresin.

The polymers obtained in Examples and Comparative Examples are subjectedto heat pressing at 160° C. to obtain dumbbell specimens, whereby thestress-strain curves (hereinafter referred to as S-S curves) weremeasured. The S-S curve was measured by means of TMI, RTM-lT testingmachine, manufactured by Toyo Baldwin Company, at 23° C. at a crossheadspeed of 10 mm/min.

S-S curves at a styrene content of about 40 mol %, 30 mol %, 20 mol %,13 mol % and 7 mol %, are shown in FIGS. 50 to 54, respectively. EachFigure shows that the copolymer of the present invention has excellentphysical properties as compared with copolymers of Comparative Examples.

The permanent elongation ratio π was obtained by the following formulafrom the ratio of the permanent elongation which is the elongationremaining after a broken dumbbell specimen is left to stand sufficientlyat room temperature, to the maximum elongation at breakage, and theresults are shown in Table 9.

π=L1/L2×100

where L1 is the permanent elongation, and L2 is the maximum elongationat breakage.

The copolymer of the present invention shows a value π of not higherthan about 10% at a styrene content of from 20 to 55 mol % and a value πof from about 10 to 30% at a styrene content of from 10 to 20 mol %,thus indicating a high elastomer property. At a styrene content of nothigher than 10%, it shows a value π of at least 30%, thus indicating aphysical property similar to LLDPE.

FIG. 55 shows the change with time, when the operation of stretching adumbbell specimen to 200%, followed by releasing, was repeated. Thisindicates a high level of elastic recovery of the copolymer of thepresent invention.

To show the effects of the crystallinity of the copolymer of the presentinvention on the physical properties, evaluation was carried out bychanging the crystallinity of the copolymer. S-S curves of the copolymerof the present invention obtained by changing the crystallinity, areshown in FIGS. 55 and 56.

Improvement of the crystallinity may be made by an addition of a filleror the like. However, in order to eliminate the effects of the filleritself on the physical properties, a simple method of dipping in asolvent was carried out. The copolymer obtained in Example 9 wassubjected to heat pressing to form dumbbell specimens, which wereimmersed in hexane and acetone, respectively, for one week, and then thesolvents were removed at room temperature for one day and further at 40°C. for one day under vacuum, to improve the crystallinity.

The heat of crystal fusion calculated from the area of the melting pointpeak by DSC, was about 30 J/g.

On the other, the same copolymer obtained in Example 9 was subjected toheat pressing, and then put into liquid nitrogen for quenching to obtainan amorphous copolymer. No melting point was observed by DSC.

It is evident that the breaking strength remarkably increases byintroducing the crystal structure (FIG. 56).

The copolymer obtained in Example 10 was subjected to heat pressing toform dumbbell specimens, which were subjected to annealing at 78° C. for5 days. The heat of crystal fusion calculated from the area of themelting point peak by DSC, was about 20 J/g. When no annealing wascarried out, the heat of crystal fusion was not higher than about 10J/g. It is evident that the breaking strength and the initial tensilemodulus can be remarkably increased by increasing the crystallinity(FIG. 57).

Further, the copolymer obtained in Example 11 (styrene content: about 50mol %) was also subjected to a method of dipping in a solvent toincrease the crystallinity. The initial tensile modulus was about 800MPa and shows physical properties similar to plastics. The heat ofcrystal fusion calculated from the area of the melting point peak by DSCwas about 20 J/g. On the other hand, without such treatment forcrystallization, the same copolymer was subjected to heat pressing toform dumbbell specimens, whereupon the S-S curve was measured, wherebythe initial tensile modulus was about 500 MPa, and the heat of crystalfusion was not higher than 10 J/g.

As described in the foregoing, the copolymer with a styrene content ofabout 50 mol % shows physical properties similar to plastics, andbecomes closer to plastics as the crystallinity increases.

The copolymer of the present invention also shows excellent solventresistance. In Table 10, the results of dipping the copolymers ofExamples and other resins in hexane and acetone, are shown. The dippingtests were carried out by dipping dumbbell specimens in the respectivesolvents for one week, and the degree of swelling was obtained from theweight change between before and after the dipping. The copolymer of thepresent invention shows excellent solvent resistance at various styrenecontents.

The transparency (Haze, total light transmittance) of the copolymerobtained in each Example was measured. The copolymer of the presentinvention has transparency equivalent to usual transparent elastomers.The results are shown in Table 11.

TABLE 9 Styrene Permanent content elongation (mol %) ratio π (%) Example1 39.1 10 Example 2 31.7 5 Example 6 17.7 27 Example 7 7.3 63 Example 812.8 30 Example 10 43.5 5 Example 11 49.3 10 Comparative 43.0 10 Example1 Comparative 21.1 10 Example 2 Comparative 13.0 30 Example 6

TABLE 10 Dipping in Dipping in hexane acetone Example 1 ⊚ ⊚ Example 2 ◯⊚ Example 6 ◯ ⊚ Example 7 — — Example 8 ◯ ⊚ Example 9 ◯ ⊚ Example 10 ⊚ ◯Example 11 ⊚ ◯ SEBS (H1041) X ◯ PVC (SK-05253) Δ X *1 ENGAGE (Ethylene-X ⊚ octene copolymer) (EG-8150) SBS (STR1602) X X Hydrogenated SBR X X(DR1910P) ⊚: No change, Degree of swelling: Less than 25% ◯: Swelled,Degree of swelling: 25 to 50% Δ: Solidified X: Gelled or dissolvedDegree of swelling = Weight increase/Original weight before dipping ×100 *1: Plasticizer eluted and the sample became brittle.

TABLE 11 Thickness Total light of speciment Haze transmittance Example 60.76 mm 24.3 77.2 Example 7 0.60 mm 15.5 87.3 Example 8 0.83 mm 22.683.5 Example 9 0.63 mm 20.8 82.7 Example 10 0.80 mm 41.5 87.5 Example 110.62 mm 24.3 87.9 SEBS (H1041) 0.91 mm 11.1 84.1 SBS (STR1602) 0.87 mm26.0 89.0 PVC (SK-05253) 0.70 mm 8.9 88.4

As described in the foregoing, according to the present invention, it ispossible to provide an ethylene-aromatic vinyl compound copolymer whichhas not been available heretofore, wherein the alternating structure ofethylene and an aromatic vinyl compound contained in theethylene-aromatic vinyl compound copolymer is lower than a certainproportion, and the aromatic groups in the alternating structure havestereoregularity and thus present an isotactic structure, and a methodfor its production.

What is claimed is:
 1. An ethylene-aromatic vinyl compound copolymerhaving an aromatic vinyl compound content of from 1 to less than 55% bymolar fraction, which has a haze of at most 41.5% when molded; whereinthe stereoregularity of the aromatic vinyl compound groups in thealternating structure of ethylene and an aromatic vinyl compoundrepresented by the following formula (1) contained in its structure, isrepresented by an isotactic diad index m of more than 0.75, and thealternating structure index λ represented by the following formula (i)is smaller than 70 and larger than 1: λ=A3/A2×100  (i) where A3 is thesum of areas of three peaks a, b and c attributable to anethylene-aromatic vinyl compound alternating structure represented bythe following formula (1′), obtained by 13C-NMR, and A2 is the sum ofareas of peaks attributable to the main chain methylene and methinecarbon, as observed within a range of from 0 to 50 ppm by 13C-NMR usingTMS as standard,

where Ph is an aromatic group, and xa is an integer of at least 2representing the number of repeating units,

wherein Ph is an aromatic group, and xa is an integer of at least 2representing the number of repeating units.
 2. The ethylene-aromaticvinyl compound copolymer according to claim 1, which is a transparentethylene-aromatic vinyl compound elastomer having an aromatic vinylcompound content of from 20 to less than 55% by molar fraction, apermanent elongation ratio π of at most 10% and a haze of at most 41.5%.3. The ethylene-aromatic vinyl compound copolymer according to claim 1,which is a transparent ethylene-aromatic vinyl compound elastomer havingan aromatic vinyl compound content of from 10 to less than 20% by molarfraction, a permanent elongation ratio π of from 10 to 30% and a haze ofat most 24.3%.
 4. The ethylene-aromatic vinyl compound copolymeraccording to claim 1, which has a melting point of from 55 to 130° C. 5.The ethylene-aromatic vinyl compound copolymer according to claim 1,wherein the aromatic group is a phenyl group.
 6. The ethylene-aromaticvinyl compound copolymer according to claim 1, which has a head-to-tailbond structure comprising two aromatic vinyl compound units.
 7. A moldedproduct of the copolymer according to claim
 1. 8. The ethylene-aromaticvinyl compound copolymer according to claim 1, which has a total lighttransmittance of at least 77.2% when molded into a specimen with athickness of from 0.60 to 0.83 mm.
 9. The ethylene-aromatic vinylcompound copolymer according to claim 1, wherein the aromatic vinylcompound content in the copolymer is at least 1% and less than 10% bymolar fraction, and the haze is at most 15.5%.
 10. A compositioncomprising the ethylene-aromatic vinyl compound copolymer according toclaim 1 and a plasticizer.
 11. A composition comprising theethylene-aromatic vinyl compound copolymer according to claim 1 and afiller.
 12. An ethylene-aromatic vinyl compound copolymer having anaromatic vinyl compound content of from 1 to less than 55% by molarfraction, which has a haze of at most 41.5% when molded, which comprisesa structure represented by the following formula (2) as the mainstructure, wherein the index θ represented by the following formula(ii), is larger than 70 when the aromatic vinyl compound content issmaller than 45% by molar fraction, or larger than 50 when the aromaticvinyl compound content is at least 45% by molar fraction: θ=A1/A2×100  (ii) wherein A1 is the sum of areas of peaks attributableto methine and methylene carbon α to ε in the following formula (2′) asobserved within a range of from 0 to 50 ppm by 13C-NMR using TMS asstandard, and A2 is the sum of areas of peaks attributable to the mainchain methylene and methine carbon, as observed within a range of from 0to 50 ppm by 13C-NMR using TMS as standard:

where Ph is an aromatic group, xb is an integer of at least 2representing the number of repeating units, y is an integer of at least1, which may be the same or different among the respective repeatingunits, and z is 0 or 1, which may be the same or different among therespective repeating units,

where Ph is an aromatic group, xb is an integer of at least 2representing the number of repeating units, y is an integer of at least1, which may be the same or different from the respective repeatingunits, and z is 0 or 1, which may be the same or different among therespective repeating units.
 13. A composition,comprising theethylene-aromatic vinyl compound copolymer according to claim 12 and aplasticizer.
 14. A composition comprising the ethylene-aromatic vinylcompound copolymer according to claim 12 and a filler.
 15. Theethylene-aromatic vinyl compound copolymer according to claim 12,wherein the aromatic group is a phenyl group.
 16. A molded product ofthe copolymer according to claim
 12. 17. The ethylene-aromatic vinylcompound copolymer according to claim 12, which has a head-to-tail bondstructure comprising two aromatic vinyl compound units.
 18. Theethylene-aromatic vinyl compound copolymer according to claim 12, whichis a transparent ethylene-aromatic vinyl compound elastomer having anaromatic vinyl compound content of from 20 to less than 55% by molarfraction, a permanent elongation ratio π of at most 10% and a haze of atmost 41.5%.
 19. The ethylene-aromatic vinyl compound copolymer accordingto claim 12, which is a transparent ethylene-aromatic vinyl compoundelastomer having an aromatic vinyl compound content of from 10 to lessthan 20% by molar fraction, a permanent elongation ratio π of from 10 to30% and a haze of at most 24.3%.
 20. The ethylene-aromatic vinylcompound copolymer according to claim 12, which has a melting point offrom 55 to 130° C.
 21. A composition obtained by blending a plurality ofcopolymers according to claim 12 having different aromatic vinylcompound contents.
 22. A composition obtained by blending a plurality ofcopolymers having different aromatic vinyl compound contents, whereinthe copolymers are selected from the group consisting ofethylene-aromatic vinyl compound copolymers having an aromatic vinylcompound content of from 1 to less than 55% by molar fraction, which hasa haze of at most 41.5% when molded; wherein the stereoregularity of thearomatic vinyl compound groups in the alternating structure of ethyleneand an aromatic vinyl compound represented by the following formula (1)contained in its structure, is represented by an isotactic diad index mof more than 0.75, and the alternating structure index λ represented bythe following formula (i) is smaller than 70 and larger than 1:λ=A3/A2×100  (i) where A3 is the sum of areas of three peaks a, b and cattributable to an ethylene-aromatic vinyl compound alternatingstructure represented by the following formula (1′), obtained by13C-NMR, and A2 is the sum of areas of peaks attributable to the mainchain methylene and methine carbon, as observed within a range of from 0to 50 ppm by 13C-NMR using TMS as standard,

where Ph is an aromatic group, and xa is an integer of at least 2representing the number of repeating units,

wherein Ph is an aromatic group, and xa is an integer of at least 2representing the number of repeating units.
 23. An ethylene-aromaticvinyl compound copolymer having an aromatic vinyl compound content offrom 1 to less than 55% by molar fraction, wherein the stereoregularityof Ph groups in the alternating structure of ethylene and an aromaticvinyl compound represented by the following formula (1′) contained inits structure, is represented by an isotactic diad index m of more than0.75, and the alternating structure index λ represented by the followingformula (i) is smaller than 70 and larger than 1: λ=A3/A2×100  (i) whereA3 is the sum of areas of three peaks a, b and c attributable to anethylene-aromatic vinyl compound alternating structure represented bythe following formula (1′), obtained by 13C-NMR, and A2 is the sum ofareas of peaks attributable to the main chain methylene and methinecarbon, as observed within a range of from 0 to 50 ppm by 13C-NMR usingTMS as standard,

where Ph is an aromatic group selected from the group consisting ofphenyl, p-methyl-substituted phenyl, m-methyl-substituted phenyl,o-methyl-substituted phenyl, o-t-butyl-substituted phenyl,m-t-butyl-substituted phenyl, p-t-butyl-substituted phenyl,p-chloro-substituted phenyl, o-chloro-substituted phenyl, andvinyl-substituted phenyl, and xa is an integer of at least 2representing the number of repeating units.
 24. The ethylene-aromaticvinyl compound copolymer according to claim 23, which comprises astructure represented by the following formula (2′) as the mainstructure, wherein the index θ represented by the following formula(ii), is larger than 70 when the aromatic vinyl compound content issmaller than 45% by molar fraction, or larger than 50 when the aromaticvinyl compound content is at least 45% by molar fraction:θ=A1/A2×100  (ii) where A1 is the sum of areas of peaks attributable tomethine and methylene carbon α to ε in the following formula (2′) asobserved within a range of from 0 to 50 ppm by 13C-NMR using TMS asstandard, and A2 is the sum of areas of peaks attributable to the mainchain methylene and methine carbon, as observed within a range of from 0to 50 ppm by 13C-NMR using TMS as standard,

where Ph is an aromatic group selected from the group consisting ofphenyl, p-methyl-substituted phenyl, m-methyl-substituted phenyl,o-methyl-substituted phenyl, o-t-butyl-substituted phenyl,m-t-butyl-substituted phenyl, p-t-butyl-substituted phenyl,p-chloro-substituted phenyl, o-chloro-substituted phenyl, andvinyl-substituted phenyl, and xb is an integer of at least 2representing the number of repeating units, y is an integer of at least1, which may be the same or different among the respective repeatingunits, and z is 0 or 1, which may be same or different among therespective repeating units.
 25. An ethylene-aromatic vinyl compoundcopolymer having, an aromatic vinyl compound content of from 1 to lessthan 55% by molar fraction, wherein the stereoregularity of Ph groups inthe alternating structure of ethylene and an aromatic vinyl compoundrepresented by the following formula (1″) contained in its structure, isrepresented by an isotactic diad index m of more than 0.75, and thealternating structure index λ represented by the following formula (i)is smaller than 70 and larger than 1: λ=A3/A2×100  (i) where A3 is thesum of areas of three peaks a, b and c attributable to anethylene-aromatic vinyl compound alternating structure represented bythe following formula (1″), obtained by 13C-NMR, and A2 is the sum ofareas of peaks attributable to the main chain methylene and methinecarbon, as observed within a range of from 0 to 50 ppm by 13C-NMR usingTMS as standard,

where Ph is a phenyl group, and xa is an integer of at least 2representing the number of repeating units.
 26. The ethylene-aromaticvinyl compound copolymer according to claim 25, which comprises astructure represented by the following formula (2″) as the mainstructure, wherein the index θ represented by the following formula(ii), is larger than 70 when the aromatic vinyl compound content issmaller than 45% by molar fraction, or larger than 50 when the aromaticvinyl compound content is at least 45% by molar fraction:θ=A1/A2×100  (ii) where A1 is the sum of areas of peaks attributable tomethine and methylene carbon α to ε in the following formula (2″) asobserved within a range of from 0 to 50 ppm by 13C-NMR using TMS asstandard, and A2 is the sum of areas of peaks attributable to the mainchain methylene and methine carbon, as observed within a range of from 0to 50 ppm by 13C-NMR using TMS as standard,

where Ph is a phenyl group, xb is an integer of at least 2 representingthe number of repeating units, y is an integer of at least 1, which maybe the same or different among the respective repeating units, and z is0 or 1, which may be same or different among the respective repeatingunits.
 27. The ethylene-aromatic vinyl compound copolymer according toclaim 23, which has a head-to-tail bond structure comprising twoaromatic vinyl compound units.
 28. The ethylene-aromatic vinyl compoundcopolymer according to claim 23, which shows substantially no peak inthe vicinity of from 40 to 41 ppm by 13C-NMR using TMS as standard. 29.The ethylene-aromatic vinyl compound copolymer according to claim 23,wherein the aromatic vinyl compound content in the copolymer is from 10to less than 55% by molar fraction.
 30. The ethylene-aromatic vinylcompound copolymer according to claim 23, wherein the alternatingstructure index λ is smaller than 70 and larger than
 5. 31. Theethylene-aromatic vinyl compound copolymer according to claim 23,wherein the stereoregularity of Ph groups in the alternating structureof ethylene and an aromatic vinyl compound, is represented by anisotactic diad index m of more than 0.85.
 32. The ethylene-aromaticvinyl compound copolymer according to claim 23, wherein thestereoregularity of Ph groups in the alternating structure of ethyleneand an aromatic vinyl compound, is represented by an isotactic diadindex m of more than 0.95.
 33. The ethylene-aromatic vinyl compoundcopolymer according to claim 23, which has a weight average molecularweight of at least 30,000.
 34. The ethylene-aromatic vinyl compoundcopolymer according to claim 23, which is a transparent ethylenearomatic vinyl compound copolymer.
 35. The ethylene-aromatic vinylcompound copolymer according to claim 23, wherein said aromatic vinylcompound is styrene.
 36. The ethylene-aromatic vinyl compound copolymeraccording to claim 23, wherein the aromatic vinyl compound content isfrom 7.2 to 52% by molar fraction.
 37. A molded product of theethylene-aromatic vinyl compound copolymer according to claim
 23. 38. Acomposition comprising the ethylene-aromatic vinyl compound copolymeraccording to claim 23 and a plasticizer.
 39. The copolymer according toclaim 23, which has a crystalline structure.
 40. A compositioncomprising the ethylene-aromatic vinyl compound copolymer according toclaim 23, and a filler.
 41. A composition obtained by blending aplurality of copolymers according to claim 23, having different aromaticvinyl compound contents.
 42. A composition, comprising theethylene-aromatic vinyl compound copolymer according to claim 23 and ablowing agent.
 43. A composition, comprising the ethylene-aromatic vinylcompound copolymer according to claim 23 and a lubricant.
 44. Thecomposition according to claim 40, which has a crystalline structure.